The Collaborative International Dictionary of English v.0.48:

Zeal \Zeal\, v. i.
   To be zealous. [Obs. & R.] --Bacon.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Zeal \Zeal\ (z[=e]l), n. [F. z[`e]le; cf. Pg. & It. zelo, Sp.
   zelo, celo; from L. zelus, Gr. ?, probably akin to ? to boil.
   Cf. Yeast, Jealous.]
   [1913 Webster]
   1. Passionate ardor in the pursuit of anything; eagerness in
      favor of a person or cause; ardent and active interest;
      engagedness; enthusiasm; fervor. "Ambition varnished o'er
      with zeal." --Milton. "Zeal, the blind conductor of the
      will." --Dryden. "Zeal's never-dying fire." --Keble.
      [1913 Webster]

            I bear them record that they have a zeal of God, but
            not according to knowledge.           --Rom. x. 2.
      [1913 Webster]

            A zeal for liberty is sometimes an eagerness to
            subvert with little care what shall be established.
                                                  --Johnson.
      [1913 Webster]

   2. A zealot. [Obs.] --B. Jonson.
      [1913 Webster]

WordNet (r) 3.0 (2006):

zeal
    n 1: a feeling of strong eagerness (usually in favor of a person
         or cause); "they were imbued with a revolutionary ardor";
         "he felt a kind of religious zeal" [syn: ardor, ardour,
         elan, zeal]
    2: excessive fervor to do something or accomplish some end; "he
       had an absolute zeal for litigation"
    3: prompt willingness; "readiness to continue discussions";
       "they showed no eagerness to spread the gospel"; "they
       disliked his zeal in demonstrating his superiority"; "he
       tried to explain his forwardness in battle" [syn:
       readiness, eagerness, zeal, forwardness]

Moby Thesaurus II by Grady Ward, 1.0:

180 Moby Thesaurus words for "zeal":
   abandon, acquiescence, agitation, agreeability, agreeableness,
   alacrity, all-overs, amenability, angst, anxiety, anxiety hysteria,
   anxiety neurosis, anxious bench, anxious concern, anxious seat,
   anxiousness, apprehension, apprehensiveness, ardency, ardor,
   avidity, bibliolatry, bluster, brawl, broil, brouhaha, cacophony,
   calenture, cankerworm of care, care, chaos, charismatic gift,
   charismatic movement, charismatic renewal, cheerful consent,
   commitment, committedness, commotion, compliance, concern,
   concernment, consent, cooperativeness, dedication, devotedness,
   devotion, devoutness, disquiet, disquietude, distress, disturbance,
   docility, dread, eagerness, earnestness, ebullition, ecstasy,
   embroilment, energy, enthusiasm, excitement, faith, faithfulness,
   fanaticism, favorable disposition, favorableness, fear, ferment,
   fervency, fervidness, fervor, fidelity, fierceness, fire, flap,
   fomentation, foofaraw, foreboding, forebodingness, forwardness,
   frenzy, fume, furor, furore, fury, fuss, gameness, gift of tongues,
   glossolalia, goodwill, gusto, heart, heartiness, heat, heatedness,
   hubbub, hurrah, impassionedness, inquietude, intensity, intentness,
   keenness, liveliness, loyalty, malaise, misgiving, nervous strain,
   nervous tension, nervousness, overanxiety, overdevoutness,
   overpiousness, overreligiousness, overrighteousness,
   overzealousness, pandemonium, passion, passionateness,
   pentecostalism, perturbation, pins and needles, pliability,
   pliancy, promptness, pucker, racket, rage, readiness,
   receptive mood, receptiveness, receptivity, relish, resolution,
   responsiveness, revival, revivalism, right mood, row, ruckus,
   rumpus, sanctimony, savor, seriousness, sincerity, solicitude,
   soul, spirit, stew, storminess, strain, suspense, tempestuousness,
   tension, tractability, trouble, tumult, tumultuousness, turbulence,
   turmoil, uneasiness, ungrudgingness, unloathness, unquietness,
   unreluctance, uproar, upset, urgency, vehemence, verve, vexation,
   warmth, warmth of feeling, wildness, willing ear, willing heart,
   willingness, zealotism, zealotry, zealousness, zest



Easton's 1897 Bible Dictionary:

Zeal
   an earnest temper; may be enlightened (Num. 25:11-13; 2 Cor.
   7:11; 9:2), or ignorant and misdirected (Rom. 10:2; Phil. 3:6).
   As a Christian grace, it must be grounded on right principles
   and directed to right ends (Gal. 4:18). It is sometimes ascribed
   to God (2 Kings 19:31; Isa. 9:7; 37:32; Ezek. 5:13).


The Devil's Dictionary (1881-1906):

ZEAL, n.  A certain nervous disorder afflicting the young and
inexperienced.  A passion that goeth before a sprawl.

    When Zeal sought Gratitude for his reward
    He went away exclaiming:  "O my Lord!"
    "What do you want?" the Lord asked, bending down.
    "An ointment for my cracked and bleeding crown."
                                                            Jum Coople